With heat and humidity building in the Chicago area, an air quality alert has been issued as officials warn of elevated ozone and particulate levels.
According to the National Weather Service, the alert covers a wide swath of the Chicago area, including McHenry, Lake, Kane, DuPage, Kendall, Grundy, Cook and Will counties.
The alert will remain in effect through at least midnight Sunday, though air quality concerns will persist at least into Monday, with the Illinois Environmental Protection Agency declaring an Air Pollution Action Day for Monday.
According to officials, an air quality alert is issued when “conditions are such that widespread ozone and/or particulate levels are expected to be at or above the unhealthy for sensitive groups category for multiple days.”
According to AirNow, the Chicago area is forecast to have an Air Quality Index (AQI) between 100 and 150 on Sunday afternoon and on Monday.
Individuals with pulmonary illnesses and other risk factors such as asthma, children and teens, older adults, and individuals who are routinely active outdoors for six or more hours per day should reduce exposure outdoors during the alert, according to officials.
They should also consider reducing the amount of time they are active while the alert is in place.
The AQI is measured based on five major air pollutants, including ground-level ozone, particle pollution and others. Ozone levels tend to be elevated during spells of hot weather, and more particle pollution occurs when residents use air conditioning units in their homes and businesses.
More information on air quality can be found on the AirNow website.